U.S. Pat. No. 4,298,025, which is owned by the present assignee, discloses a control valve for use in water softeners having two resin tanks. One of the resin tanks is normally on-line while the other tank is regenerated and placed in a standby condition until the first tank requires regeneration. The disclosed control valve controls which of the tanks is on-line and controls the regeneration sequence of an exhausted tank.
The quantity of water treated by a given tank, is monitored by a mechanism that includes a water usage turbine driven by water entering the on-line resin tank. When a predetermined quantity of water is treated, which produces to a predetermined number of revolutions in the turbine, a regeneration sequence is initiated which places the standby tank on-line and isolates the exhausted tank.
A second turbine, operatively connected to a regeneration sequence control element (in the form of a disk) is rotated by a stream of water that is activated at the beginning of the regeneration cycle. The stream of water physically drives the regeneration control disk (via the turbine and associated drive train) through its sequence. With the disclosed arrangement, the frequency of regeneration of the water softener system is determined by the usage turbine which directly measures the quantity of fluid treated by a given tank.
In U.S. Pat. No. 4,427,549 which is also owned by the present assignee, a deionization method and apparatus is disclosed. The disclosed apparatus includes a control valve similar to the control valve disclosed in U.S. Pat. No. 4,298,025 in that it includes a usage turbine for monitoring the amount of source water treated by a given tank and a regeneration control turbine for driving a control element through a regeneration sequence.
The control valves disclosed in U.S. Pat. Nos. 4,298,025 and 4,427,549 channel all water to be treated past the water usage turbine. For the valves disclosed in these patents, the flow rate is sustainable through the valve is in large measure determined by the flow rate that is sustainable through the passages conveying the water to the water usage turbine. Attempts have been made to improve the flow rate of the types of control valves disclosed in the above-identified patents.
U.S. Pat. No. 5,490,932, which is also owned by the present assignee and is hereby incorporated by reference, discloses a dual nozzle arrangement which increases the maximum flow rate through the valve of the water to be treated. In the control valve disclosed in the patent, two nozzles simultaneously feed water to the usage turbine.
It has been found that in some water treatment applications, the flow rate of water through the valve can vary substantially. It has been found, for example, that in some systems the flow rate can vary between 0.05 gallons per minute to 30 gallons per minute. It has been found that in water treatment applications where water flow rates vary between extremely wide limits, the accuracy of the monitoring mechanism may be adversely affected. For example, at very low flow rates of fluid, as might occur due to leaks in the plumbing system, little or no rotation in the water usage turbine is produced. Hence, this leakage water, although treated by the treatment apparatus, i.e., water softener, would not produce proportional movement in the monitoring mechanism and, as a result, the online resin tank could be used beyond exhaustion before it is regenerated.
The monitoring inaccuracy caused by low water flow rates was also found to be present in plumbing systems that utilize storage tanks from which the treated water was called for as needed. In these types of systems, water delivered from the storage tank to a shower or washing machine was delivered at a relatively high flow rate. However, as the storage tank was refilled or replenished, the flow rate of the water refilling the tank gradually decreased as the tank level control valve neared closure. In some systems, the level control valve would allow water to “dribble” into the tank for a considerable amount of time before complete closure occurred. The water treatment apparatus, i.e., water softener, is usually located upstream of the storage tank. The relatively low water flow rate of the replenishment water passing through the water softener in some instances was not sufficient to produce proportional movement in the water monitoring mechanism, resulting in a treatment tank being left online beyond exhaustion.